The present invention relates to electrophotographic or electrostatic image forming equipment such as a copier, facsimile apparatus or printer and, more particularly, to image forming equipment of the type supplying a toner to a developing apparatus thereof by using a toner cartridge filled with a toner.
Image forming equipment of the type described has a developing device or unit which is loaded with a toner for developing a latent image electrostatically formed on an image carrier. A prerequisite with such equipment is that every time the toner is consumed to a predetermined degree, a supplementary amount of toner be fed to the developing unit. Conventional toner supply systems may generally be classified into two types, i.e., a system of the type directly supplying a to a toner hopper or similar supply section and a system of the type supplying a toner from a toner cartridge which is removably located at a toner supply position above the opening of a toner hopper. Today, the cartridge type system is predominant over the directly supply system because the latter is apt to cause the toner to scatter about to smear not only the equipment but also the operator's hands and cloths during the supply.
Even the cartridge type system has a problem left unsolved, as follows. When the amount of toner remaining in the developing unit decreases beyond a predetermined amount, the operator is expeted to unseal a new toner cartridge and substitute it for the toner cartridge existing in the equipment. When the operator strips a seal member from an opening which is formed in the new cartridge for supplying a toner, the toner deposited on the seal member is apt to sprinkle to smear the equipment and the operator's hands and cloths. To eliminate this problem, it has been proposed to dispose unsealing means in the toner supply position such that when a toner cartridge is inserted toward the toner supply position, the unsealing means contacts and cuts the seal member, as disclosed in, for example, Japanese Patent Laid-Open Publication No. 188182/1988 and Japanese Utility Mode Laid-Open Publication No. 122363/1988.
The above prior art unsealing scheme starts unsealing a cartridge as soon as the cartridge is inserted toward the toner supply position. This brings about a problem that when the operator interrupts the insertion of a cartridge noticing that the cartridge is not the one containing a desired color or having a proper size or that the orientation thereof is not correct, the seal of the cartridge has already been partly stripped. Should such a partly unsealed cartridge be pulled out from the equipment, the toner contained therein would be sprinkled to the inside and outside of the equipment. Moreover, the seal member cut by the unsealing section has the portions thereof adjoining the edges of the cartridge bent into the cartridge. The toner, therefore, remains between the bent portions of the seal member and the walls of the cartrige and is simply wasted.
Another problem with the conventional cartridge type system is that the operator has to replace the used toner cartridge with new one by removing the used cartridge by hand. Then, the toner adhered to the inner walls of the used cartridge is apt to contaminate the equipment and the hands and cloths by being sprinkled to the inside and outside of the equipment. In light of this, there has been proposed a toner supply system using a plurality of cartridges each having a particular size, as taught in, for example, Japanese Patent Laid-Open Publication No. 188171/1988. When one of the plurality of cartridges is to be located at the toner supply position of the developing unit, it is fitted in the preceding cartridge which is empty. In this manner, the cartridges sequentially brought to the toner supply position are each fitted in the preceding empty cartridge in a laminate core configuration. This allows the operator to supply a fresh toner to the developing unit without pulling out the empty cartridge.
However, the problem with the toner supply system using a plurality of cartridges as mentioned above is that when a new cartridge is forced into the empty cartridge remaining in the toner supply position, it generates a stream of air with the result that the toner remaining in the empty cartridge is scattered about to the inside and outside of the equipment. The empty cartridges in a laminate core configuration have to be removed from the equipment while sliding on members which define the toner supply position. Such an operation is troublesome. Moreover, it is likely that the toner adhered to the outermost empty cartridge is splinked. A mechanism for aligning an opening where a cartridge should be located and the opening of a toner hopper and a mechanism for preventing a toner from being sprinkled into the equipment via the hopper opening are densely arranged at the toner supply position. This forces the operator to take greatest care when inserting a cartridge to the toner supply position. Further, the operator has to locate a cartridge at the toner supply position accurately with the greatest care. In addition, the stack of empty cartridges have to be pulled out from the toner supply position via the limited space therearound.